Savageborn Hydra $8 Random Hydras are probably worth more than you think
Hate Mirage is also pretty good for us: copying a Solemn Simulacrum and another value non-Human gives us EtB triggers, attack triggers, and potentially death triggers too, all for four mana
Thats usually more than enough to overwhelm the table, especially when every attack trigger and token maker fires off multiple times
Second, well usually not need cards in hand since we can combo off from the graveyard with Underworld Breach
Technically, Sultai Morphs comes in first, thanks in large part to Seedborn Muse and Tempt with Discoverytwo of the most valuable reprints in the entirety of Commander 2019 , although Jeskai Flashback isn't far behind, making up for the lack of high-end reprints with a bunch of cards in the $3 range